According to the structure, Instrument pipeline self-limiting temperature electric heating cable used for tracing heat of instrument pipeline can be divided into three categories.Constant power electric heat trace cable, self-limiting temperature electric tracing cable and metal armoured heating cable.Instrument pipeline and tracing hot strip can compensate for the actual heat demand, so it is a new generation of energy-saving electric tracing products.Quick start at low temperature, uniform temperature, easy installation, simple maintenance, high automation level, low operation and maintenance costs.It is safe and reliable, does not pollute the environment, and has a long life. It can be used not only in common areas, dangerous areas, flat ribbon cable but also in corrosion areas.The principle is to install heating elements between the insulation layer and the heat-tracked object to supply the heat lost in the process of transmission and storage by sending out electric heat, so as to maintain the heat-tracked medium in a certain temperature range.
There are two kinds of instrument heat tracing in petrochemical plant: process heat tracing: the medium in the instrument pressure guide tube loses a certain amount of heat due to the difference of surrounding temperature, and it needs electric heating to reach the required surface temperature.It is often used in waxy, condensable and gasifiable materials to avoid precipitation, deposition, sudden increase of viscosity and increase of flow resistance due to lower temperature.The heat tracing temperature shall be determined by the technology specialty according to the physical properties of the heat tracing medium.Anti-freezing system: to prevent the freezing or solidification of medium in the guide pipe of instrument in winter.Usually used in the measurement of water, steam and other materials, the maintenance temperature of this type should be kept at a minimum of 5 degrees.It should be noted that petrochemical plants are mostly in explosion-proof dangerous zones. When choosing the type of accompanying tropical zone, special attention should be paid to the temperature group of explosive dangerous release medium (TClass) and the maximum maintenance temperature of heat tracing pipeline to meet the requirement that the maximum maintenance temperature is not higher than the temperature group of explosive release medium.http://www.tiankangcable.com/Heat-Trace-Cable.html
Instrument pipeline self-limiting temperature electric heating cable Tropics
Self-limiting electric tracing tropical zone is also known as “self-limiting tracing tropical zone”.It covers a flat layer of FTC (positive resistance temperature coefficient) heating material evenly between two parallel wires. When the power supply is connected with the tropical zone (note that the tail end core can not be connected), the current from one conductor core to the other core forms a loop through the conductive PTC material.When the core temperature rises to a certain value, the resistance is almost blocked, and the temperature is no longer increased. At the same time, the heat transfer from the core to the heated system with lower temperature is accompanied by the heat transfer.The power of the electric tracer is mainly controlled by the heat transfer process. The output power is automatically adjusted with the temperature of the heated system, but the traditional constant power heater has no such function.http://www.tiankangcable.com/flat-ribbon-cable.html
(1) Copper core conductor: 7 x 0.50; 7 x 0.32; 19 x 0.41; 2) conductive plastic layer: ordinary PTC; flame retardant PTC; fluorinated PTC; 3) insulating layer: modified polyolefin; flame retardant polyolefin; fluorinated polyolefin; perfluorine material; 4) shielding layer: tin-plated soft copper wire (80% coverage density); 5) sheath layer: improved polyolefin; flame retardant polyolefin; fluorinated polyolefin; perfluorinated material; The PTC material is made by mixing a high polymer with selected carbon black in a certain proportion, under certain technical conditions, and through a certain treatment process.The resistance value of the material increases with the increase of temperature, so that the working current decreases and the output power decreases.Usually, the output power of the electric tracer is used as the rated value of the product’s power when the working temperature is 10 C.When the temperature rises to below 10% of the rated power, the temperature at this time is called the maximum maintenance temperature.If the temperature continues to rise until the molecular structure of PTC material is destroyed, the temperature at this time is called the maximum withstanding temperature of electric companion tropics.The maximum withstanding temperature of the product is more than 200 C, generally not more than 230 C.The outer layer of PTC material is an insulating layer consisting of an elastic thermoplastic body with high temperature resistance. It tightly encloses PTC material, but it can not bond with PTC material boat cable.
Constant Power Electric Tracing Tropics
Constant power electric tracing strip, winding nickel-chromium electric heating wire on the inner sheath insulation layer, and using electric heating wire and two buses staggered at a certain interval to form a continuous parallel resistance.When the power supply is added to two buses, the parallel resistors heat simultaneously, forming a continuous “strip heater” style.The heat output per unit length of the accompanying tropical zone is constant, and is not affected by ambient temperature and pipeline temperature. http://www.tiankangcable.com/marine-cable.html The longer the accompanying tropical zone is used, the greater the total heating power is.It can be sheared according to the length of use during installation.As the tail voltage of the electric tracer decreases with the increase of length, it is not advisable to exceed the recommended maximum length for installation.The electric tracing belt has good flexibility and can be laid conveniently along the pipeline.Its outer metal braided layer can not only improve the overall strength of the tropical belt, but also be a safe grounding wire.The product type varies with the material of conductive core wire, metal braided layer, insulating material and structure.Conductive cores can be made of copper strands or silver-plated copper strands, metal braided layers can be made of ordinary materials or stainless steel wires, while insulating materials can be made of fluoroplastics (200 C) or polytetrafluoroethylene (PTFE) and alkali-free glass fibers (260 C). By adding insulating layers, they can be reinforced, with higher mechanical strength, stronger corrosion resistance, but lower thermal conductivity http://www.tiankangcable.com/Polyurethane-cable.html.
Metal armoured heating cable
Metal armoured heating cables are made of one or two metal conductors, which are contained in highly compressed mineral insulating materials, and are encapsulated in copper or stainless steel sheaths.Conductor and sheath materials can be selected according to actual needs.Compared with plastics, stainless steel sheaths can withstand higher temperatures and have larger heating power per unit length.Metal armoured heating cable has longer service life and greater mechanical strength, but its heating power per unit length can not be automatically adjusted, the length of use can not be arbitrarily cut off, can only be prefabricated by the factory, and its soft type is not as good as plastic electric tracing.high temperature cable
Different heating cables should be selected for different occasions and conditions.No heating cable is suitable for any situation.Firstly, the type of heating cable should be determined according to the working conditions. In the instrument pipeline heat tracing system, the main consideration is the maximum temperature which may occur when the pipeline is purged.For pipelines with medium temperature above 250 C, the wall temperature of instrument pressure guide pipe is likely to be above 200 C when the steam is blown back. At this time, plastic heating cable should not be used, and metal armoured type should be chosen.After using special fixing clamp, the medium temperature that plastic heating cable can adapt can be increased according to the actual situation, but it should be guaranteed that under the condition of steam back-blowing, the temperature of heating cable does not exceed its maximum allowable temperature. Even if the heating cable itself is not electrified at this time, it will cause permanent damage of heating cable or greatly shorten its service life.In addition, plastic heating cables should be used in general occasions http://www.tiankangcable.com/High-temperature-cable.html.
Compared with steam tracing system, Anbang instrument pipeline tracing system has the following obvious advantages:
The design and construction are simple, convenient and standardized, which is conducive to reducing the cost of design and construction; the heat tracing effect is good, and pipeline vaporization and dead-angle freezing are not easy to occur; and the steam-water discharge, pollution-free and corrosion-free are conducive to ensuring the cleanliness and hygiene of power plants.(4) Maintenance workload is small, especially under the condition of shutdown, it can keep heat tracing, instrument and transmitter; _Long maintenance period is conducive to saving maintenance and repair costs; _No loss of steam and water, reducing operation costs.polyurethane cable When heating the instrument pipeline with electric tracer, it is necessary to know the minimum ambient temperature, winter wind speed, material and thickness of insulation layer, and to determine the temperature to be maintained.In order to make the electric tracing hot strip work normally, it is suggested that the electric tracing hot strip scheme be formulated according to the actual field environment to ensure the correct installation and reliable operation of the electric tracing hot strip, to ensure the long-term stable operation of the electric tracing hot strip, to ensure the accuracy of instrument indication and the safety of equipment.